Motor vehicles may include a differential on the drive axle to transmit torque produced by an engine to driven wheels of the vehicle. The differential allows the driven wheels to rotate at different speeds relative to each other. This allows the outer wheel to rotate faster than the inner wheel when the vehicle is turning.
A typical open differential includes a ring gear meshing with a pinion gear that is fixed to a driveshaft. A differential case is fixed to the ring gear and is supported for rotation within a housing of the differential. The case supports a pair of side gears and a pair of spider gears in meshing engagement with the side gears. The side gears are driveably connected to the driven wheels. The spider gears transmit torque from the case to the side gears to propel the vehicle. Open differentials have difficulty propelling the vehicle when one of the driven wheels is on a low-traction surface as torque from the engine is routed to the low-traction wheel resulting is wheel spin.
Limited-slip differentials were developed to overcome the drawbacks of open differentials. Typical limited-slip differentials include a clutch pack and a spring that cooperate to engage a side gear, associated with the higher-traction wheel, with the case to provide engine torque to both driven wheels.
A locking differential includes a locking mechanism configured to rotationally lock the side gears relative to each other so that the left and right driven wheels rotate in unison. Unlike limited-slip differentials, which rely on wheel spin to compress the clutch pack, locking differentials include a locker that mechanically locks the half shafts for unison rotation. The locker may be manually or electronically engaged. This type of differential is commonly employed on pickup trucks and sport utility vehicles to improve off-road capabilities.